AD 98-24247

[Federal Register Volume 63, Number 178 (Tuesday, September 15, 1998)]
[Rules and Regulations]
[Pages 49269-49272]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 98-24247]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-47-AD; Amdt. 39-10739; AD 98-18-23]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 747

[[Page 49270]]

series airplanes, that currently requires repetitive high frequency 
eddy current (HFEC) inspections to detect cracking on all surfaces of 
the upper recesses in certain latch support fittings of the cargo 
doorway, and replacement of cracked fittings with new fittings. The 
existing AD also provides for optional terminating action for the 
repetitive inspections. This amendment requires accomplishment of the 
previously optional terminating action. This amendment is prompted by 
reports indicating that the repetitive inspections required by the 
existing AD may not detect cracked fittings in a timely manner. The 
actions specified by this AD are intended to prevent the cargo door 
from opening while the airplane is in flight, which could result in 
rapid decompression of the airplane.

DATES: Effective October 20, 1998.
    The incorporation by reference of Boeing Alert Service Bulletin 
747-53A2377, dated December 10, 1992, and Boeing Service Bulletin 747-
53A2377, Revision 2, dated October 6, 1994, as listed in the 
regulations, is approved by the Director of the Federal Register as of 
October 20, 1998.
    The incorporation by reference of Boeing Service Bulletin 747-
53A2377, Revision 1, dated January 28, 1993, as listed in the 
regulations, was approved previously by the Director of the Federal 
Register as of March 11, 1993 (58 FR 11190, February 24, 1993).

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, PO Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Bob Breneman, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2776; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 93-02-16, 
amendment 39-8500 (58 FR 11190, February 24, 1993), which is applicable 
to certain Boeing Model 747 series airplanes, was published in the 
Federal Register on December 11, 1997 (62 FR 65233). The action 
proposed to continue to require repetitive high frequency eddy current 
inspections to detect cracking on all surfaces of the upper recesses in 
certain latch support fittings of the cargo doorway, and replacement of 
cracked fittings with new fittings. The action also proposed to require 
accomplishment of the previously optional terminating action.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Rule

    Several commenters support the proposed rule.

Request To Revise Cost Estimate

    One commenter requests that the cost estimate for the proposed rule 
be increased to $4,500 per installation to reflect replacement of two 
truss fittings associated with each latch support fitting. The 
commenter notes that certain truss fittings [(the subject of AD 79-17-
02 R2, amendment 39-3867 (45 FR 52357, August 7, 1980)] and certain 
latch support fittings (the subject of this AD) are made of the same 
7079-T6 material. The commenter reports that it intends to replace the 
truss fittings at the same time it replaces the latch support fittings.
    The FAA does not concur that the estimated cost of replacement of 
the latch support fittings should be increased to $4,500 per 
installation. This AD does not require replacement of any truss 
fittings that are attached to the latch support fittings. Although AD 
79-17-02 R2 requires that the truss fittings be inspected, it does not 
require replacement because of the fail-safe design that incorporates 
two truss fittings for each latch support fitting. While the FAA 
acknowledges that it would be prudent for operators to replace those 
truss fittings at the same time the latch support fittings are 
replaced, this AD does not require replacement of any truss fittings. 
No change to the cost estimate of the final rule is necessary.

Request To Reduce Compliance Times

    One commenter (the Civil Aviation Authority (CAA), which is the 
airworthiness authority for the United Kingdom) requests that the 
compliance time for the proposed actions be reduced. Specifically, the 
CAA suggests that the inspections be performed at 3-month intervals and 
the latch support fittings replaced within 12 months. In support of its 
recommendation, the commenter refers to a report of an 8-inch crack 
found in a latch support fitting on a Boeing Model 747 series airplane. 
The fitting had been inspected twice in a 6-month period; no crack had 
been found during the first inspection. The commenter suggests that, 
based on the reported incident, such reduced compliance times would be 
more realistic.
    The FAA does not concur with the request to reduce the compliance 
times. The FAA finds that the proposed 18-month replacement threshold 
will provide an acceptable level of safety because of the fail-safe 
capability resulting from multiple latch support fittings. In addition, 
the 18-month compliance time will allow for the fittings to be replaced 
during scheduled maintenance at regular maintenance bases, thereby 
minimizing the impact on affected operators. The FAA recognizes the 
CAA's jurisdiction and authority to require accomplishment within its 
suggested inspection interval and replacement threshold on affected 
airplanes within the United Kingdom.

Comment Concerning Availability of Materials

    One commenter states that the 18-month replacement threshold 
required by this AD should not present a scheduling problem provided 
that materials are available from the manufacturer.
    At this time, the FAA is not aware of any scheduling difficulties 
that may delay operators' acquisition of the required materials for 
timely compliance with this AD.

Change to the Rule

    Operators should note that new paragraph (b) of the final rule has 
been revised to include an additional source of service information for 
accomplishment of the replacement. This change allows operators to 
replace the support fittings in accordance with Boeing Service Bulletin 
747-53A2377, Revision 1, dated January 28, 1993, in addition to the 
other cited versions of alert service bulletin.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the change previously 
described. The FAA has determined that this change will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 200 Boeing Model 747 series airplanes of 
the affected design in the worldwide fleet.

[[Page 49271]]

The FAA estimates that 115 airplanes of U.S. registry will be affected 
by this AD.
    The inspections that currently are required by AD 93-02-16, and 
retained in this AD, take approximately 31 work hours per airplane, per 
inspection cycle, to accomplish, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the currently 
required inspections on U.S. operators is estimated to be $213,900, or 
$1,860 per airplane, per inspection cycle.
    The new action (replacement of the latch support fittings) that is 
required by this AD will take approximately 1,019 work hours per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Required parts will cost approximately $20,917 per airplane ($12,888 
for all aft door fittings; $8,029 for all forward door fittings). Based 
on these figures, the cost impact of the new replacement requirements 
of this AD on U.S. operators is estimated to be $9,436,555, or $82,057 
per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the requirements of this 
AD action, and that no operator would accomplish those actions in the 
future if this AD were not adopted.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a 
significant economic impact, positive or negative, on a substantial 
number of small entities under the criteria of the Regulatory 
Flexibility Act. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-8500 (58 FR 
11190, February 24, 1993), and by adding a new airworthiness directive 
(AD), amendment 39-10739, to read as follows:

98-18-23  Boeing: Amendment 39-10739. Docket 97-NM-47-AD. Supersedes 
AD 93-02-16, Amendment 39-8500.

    Applicability: Model 747 series airplanes, line numbers 1 
through 200 inclusive; having 7079-T6 aluminum latch support 
fittings; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (d) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent the cargo door from opening while the airplane is in 
flight, which could result in rapid decompression of the airplane, 
accomplish the following:

Restatement of the Requirements of this AD 93-02-16

    (a) Within 60 days after March 11, 1993 (the effective date of 
AD 93-02-16, amendment 39-8500), perform a high frequency eddy 
current (HFEC) inspection to detect cracking on all surfaces of the 
upper recess in each 7079-T6 aluminum latch support fitting of the 
cargo doorway, in accordance with Boeing Service Bulletin 747-
53A2377, Revision 1, dated January 28, 1993, or Revision 2, dated 
October 6, 1994. After the effective date of this AD, only Revision 
2 of the service bulletin shall be used.

    Note 2: Boeing Service Bulletin 747-53A2377, Revision 2, dated 
October 6, 1994, references Boeing Service Bulletin 747-53-2200, 
Revision 1, dated November 16, 1979, as an additional source of 
service information for the replacement of these fittings.

    (1) If any cracking is found on any fitting, prior to further 
flight, replace the cracked fitting with a new 7075-T73 aluminum 
latch support fitting in accordance with Boeing Service Bulletin 
747-53A2377, Revision 1, dated January 28, 1993, or Revision 2, 
dated October 6, 1994. After the effective date of this AD, only 
Revision 2 of the service bulletin shall be used.
    (2) If no cracking is found on any fitting, repeat the HFEC 
inspection thereafter at intervals not to exceed 18 months until the 
requirements of paragraph (b) of this AD are accomplished.

New Requirements of This AD

    (b) Within 18 months after the effective date of this AD, 
replace all 7079-T6 aluminum latch support fittings with new 7075-
T73 fittings, in accordance with Boeing Alert Service Bulletin 747-
53A2377, dated December 10, 1992, Boeing Service Bulletin 747-
53A2377, Revision 1, dated January 28, 1993, or Boeing Service 
Bulletin 747-53A2377, Revision 2, dated October 6, 1994. Replacement 
of all latch support fittings constitutes terminating action for the 
inspection requirements of this AD.
    (c) As of the effective date of this AD, no operator shall 
install any 7079-T6 aluminum latch support fitting of the cargo door 
on any airplane.
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.
    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (e) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (f) The actions shall be done in accordance with Boeing Alert 
Service Bulletin 747-53A2377, dated December 10, 1992; Boeing 
Service Bulletin 747-53A2377, Revision 1, dated January 28, 1993; or 
Boeing Service Bulletin 747-53A2377, Revision 2, dated October 6, 
1994.
    (1) The incorporation by reference of Boeing Alert Service 
Bulletin 747-53A2377, dated December 10, 1992, and Boeing Service 
Bulletin 747-53A2377, Revision 2, dated October 6, 1994, is approved 
by the Director of the Federal Register, in accordance with 5 U.S.C. 
552(a) and 1 CFR part 51.
    (2) The incorporation by reference of Boeing Service Bulletin 
747-53A2377, Revision 1, dated January 28, 1993, was approved 
previously by the Director of the Federal Register as of March 11, 
1993 (58 FR 11190, February 24, 1993).
    (3) Copies may be obtained from Boeing Commercial Airplane 
Group, P.O. Box 3707,

[[Page 49272]]

Seattle, Washington 98124-2207. Copies may be inspected at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.
    (g) This amendment becomes effective on October 20, 1998.

    Issued in Renton, Washington, on August 28, 1998.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-24247 Filed 9-14-98; 8:45 am]
BILLING CODE 4910-13-P